Sorano was probably inhabited by Villanovan culture, but the first historical mentions are relative to the 3rd century BC, when it was an Etruscan city under the influence of the more populous nearby Sovana.

Disappearing from history under the Roman domination, it is again known in 862 when a county was founded by Emperor Louis II, under the Aldobrandeschi suzerainty.

The Aldobrandeschi were the most powerful feudataries of southern Tuscany for more than four centuries, disappearing in 1312 when Margherita, son of Ildibrandino, died without male heirs.

His daughter Adelaide married to Romano di Gentile Orsini, who added the city to the family fiefs.

The fortress, due to its strategic position, was frequently attacked; it was also the seat of fratricidal fights between the Orsini.